Unpack arguments into a command line flags using shell script-CodePudding

I am trying to create a shell script that will unpack multiple arguments and put them in a one-line with multiple flags

# How script will be run
./script "database" "collection1 collection2 collection3"

# Inside ./scipt
db=$1
collections=$2

mongodump --uri=<host:port> --db=${db} --collection=${for each argument in collections variable}

# Output should be this:
mongodump --uri=<host:port> --db=${db} --collection=collection1 --collection=collection2 --collection=collection3

The problem is how to unpack the ${collections} variable which takes space-separated arguments into an array or something and calls each collection together with the --collection flag in one line

CodePudding user response：

The ./script might be something along these lines:

#!/bin/bash

db=$1
read -ra collections <<< "$2"

echo mongodump --uri=host:port --db="$db" "${collections[@]/#/--collections=}"

Drop the echo if you're satisfied with the output. Run it as

./script "database" "collection1 collection2 collection3"

CodePudding user response：

You can split the array using IFS (Internal Field Separator), which uses space by default. Then you can loop the arguments in the array

#!/bin/bash

db=$1
collections=($2)

mongodump --uri=<host:port> --db=${db} "${collections[@]/#/--collection=}"